100mV precision 40V tolerant scalable cap free current limited voltage source for wide input current range

A 40V tolerant current limited voltage source for a wide input current range is presented. Integrated current limited voltage sources are needed for diagnosis purposes in automotive applications like airbag squib drivers that deploy airbags. The topology proposed here overcomes the conventional on chip Zener based topology that is sensitive to process variations and provides reliable operation in a multiple supply voltage environment. The poles and unity gain bandwidth of the circuit remain constant for all input currents. The circuit can be programmed to any output voltage with 100mV precision. A cap free topology is achieved such that a wide range of load capacitors from 10pF to 10μF can be connected without impacting stability. This circuit is needed in automotive applications but not limited to other applications. This circuit is fabricated in a 40V, 0.35μm BiCMOS process.